The Kenyan government has reacted angrily to a decision by the British government to block Kenya's transport minister from entering the country.

Kenya's foreign minister, Ali Chirau Makwere, says Britain has not explained why it revoked Chris Murungaru's visa. He said there was no official communication on the matter, and he called the decision "unfriendly."

He also said Britain should have followed diplomatic channels.

On Wednesday, the British High Commission in Nairobi issued an alert to airlines flying to Britain not to allow Mr. Murungaru onboard - but gave no other details.

Earlier this year, the transport minister, a close ally of President Mwai Kibaki, was demoted from his position of security minister following allegations of corruption.

Britain and the European Union have warned Kenya it risks losing foreign aid if it refuses to seriously address high level graft.